A charge accumulator is used, for example, to provide the energy needed to operate a flash lamp diode at the instant that the flash is triggered. Conventional capacitors or so-called super-caps are used as charge accumulators. A super-cap has the advantage that a high capacitance, in the farad range, for example, is available on a small surface area. Due to the low internal resistance, a high current can be output for short periods, with a low voltage drop at the super-capacitor.
In a conventional circuit, such a charge accumulator for operating a flash lamp diode coupled to a current source is charged by means of a DC/DC converter that is supplied with energy by an energy source such as a battery. The flash can be triggered after the charge accumulator has been charged up to the fixed value of a maximum voltage. Because the value of the maximum voltage is fixed, considerably more energy is stored in the charge accumulator than is necessary, depending on the forward or conducting state voltage of the flash lamp diode. This energy on the one hand must be supplied by the energy source and on the other hand must be dissipated during triggering. Since the currents required for a flash lamp diode are in the range of 2 to 5 A, the excess energy that must be drained from the current source coupled to the flash lamp diode is very large. This makes integration of this current source difficult. In some cases, rather large surface areas are needed for cooling. At the same time high requirements are placed on the energy source.